1. Field of the Invention
The present invention relates to a pumping system; and more particularly, to a pump protection algorithm for a pump in a pumping system.
2. Purpose of or Problem Solved by Invention
In known pumping systems, the system pressure is maintained constant by varying the speed of the pump. However, problems can occur with these systems when the set-point pressure is set higher than the pump can achieve. When this happens, the pump can run continuously with no flow passing through the pump. Most pumps on the market today will be damaged if they are operated in this condition. The condition described above is commonly known as a dead head condition.
Techniques are known to detect such a dead head condition; however, the pump is always turned off in order to protect it, even if the pump is able to maintain a lower pressure.
Other products and techniques are available that are designed to protect the pump from damage due to dead head or no-flow conditions. Some of these products and techniques detect these operating conditions by measuring the phase angle between the AC voltage and the AC current supplied to the motor, the system pressure, and time. In some cases, the phase angle is measured using a phase detector circuit that measures current using current transformers. However, the addition of these devices adds cost and size to these protection systems. Others measure the system pressure and magnitude of the output current. This technique can lead to false detection under certain operating conditions such as when the system is close to no flow.
In view of this, there is a need in the industry to address and solve this basic problem.